Scientific Objective To explore the pattern of centrosome inheritance at fertilization. Strategic Objective To understand the motility and architectural changes necessary for the successful completion of the fertilization process in non-human primates. Our research is aimed towards understanding the motility and architectural changes necessary for the successful completion of the fertilization process in non-human primates. Five questions are posed 1. What characterizes the organization of microtubules during fertilization in Rhesus monkeys, and does it suggest the maternal or paternal inheritance of the centrosome? This information is important in understanding centrosome heredity, fundamental aspects of the motility leading to genomic union, and possibly in the evaluation and alleviation of infertility. 2. Is there evidence for a paternal centrosome contribution during polyspermy? These experiments will show whether polyspermy is lethal solely because of a genomic imbalance, or if supernumerary centrosomes are also problematic in primates. 3. Will parthenogenetically-activated monkey oocytes organize bipolar mitotic apparatus at the time of first division? If so, this would provide an indication that the oocyte contains all the necessary constituents for spindle formation, as well as provide information on the mode of centrosome inheritance. 4. What is the role of microtubules during Rhesus fertilization? Does taxol treatment support the hypothesis that the sperm contributes the dominant, and perhaps sole, centrosome? Will zygotes recovering from microtubule inhibition form bipolar spindles in association with the male, but not female, pronucleus? These questions will be explored through the use of microtubule inhibitors. 5. What are the dynamic properties of microtubules in maturing and mature Rhesus oocytes? This knowledge may prove of importance when clinicians evaluate at which stage of meiotic maturation human oocytes should be frozen for possible later fertilization. This research will advance the understanding of genomic union during fertilization in primates, a key step in the reproductive process. Key words imaging, fertilization, motility and development, mitosis, cytoskeleton